Haskell library of efficent, purely-functional data structures

The abstract interface (API) of the Edison library for Haskell for
use with ghc.

Edison is a library of purely function data structures for Haskell
originally written by Chris Okasaki. Conceptually, it consists of two
things:

- A set of type classes defining data the following data structure
abstractions: 'sequences', 'collections' and 'associative
collections'
- Multiple concrete implementations of each of the abstractions